Butser Ancient Farm

Principal Christine Shaw

Lessons from the Pimperne House
Dismantling.

Reynolds, in Harding, Blake and Reynolds
(1993), describes in detail the thinking behind his first Great
Roundhouse project and used in the construction of the best
available interpretation of the structure of the Pimperne House
in Dorset, UK. This was undertaken in part of the grounds of The
Queen Elizabeth Country Park, South of Petersfield in Hampshire,
UK and in the shadow of Butser Hill, where his first work on Iron
Age farming began.

Work on the Pimperne House began in
1976. The house was finally dismantled in September 1990. The
lessons from the construction stage have been summarised on a previous page.

This page deals with lessons from the
dismantling stage and which were also described in Harding et al.
It should be noted that the particular discoveries made when
excavating the post holes left behind when the uprights were
removed, led to the specific hypotheses and conclusions reported
in the lecture and subsequent publication on the Life and Death of a
Post Hole.

Dismantling took place over two weeks of
work and careful observation and recording covering various
features of the building. The whole was in good structural
condition, except for the outer porch posts (the most exposed
parts) and these had already been replaced because of rotting at
the soil interface. Clearly they would have needed replacing
again quite soon.

All visible support timbers were in good
order and well secured. The worm infestation observed in the
first years after construction had penetrated no more than 2 mm
into the pith wood. This was found to be so for the rafters,
also. Only one principal post had started to rot at the soil
interface and no subsidence had occurred. Purlins, rafters and
ties were all in an excellent state. The hazel of the purlins had
set but, unlike a hurdle fence of comparable age, were not
brittle and could be used to scale the roof during inspection.
The rafters were hard and fit for reuse. Smoke blackening was
confined to the upper third of all members.

The very detailed observations of the
deterioration of the main structural posts showed that the early
stages of decay did not give the full picture of how post holes
appear in the archaeological record and it is the bridge between
these two time scales that led to the above mentioned paper
"Life and Death of a Post Hole" [link above]. Very
briefly, the early decay could be accelerated by any long-term
ingress of moisture. However, even when this occurred, the first
stage of decay left the bark intact and, where the pith wood
rotted rapidly, an air gap developed which generally led to the
remaining central hard wood being dry and long lasting. Thus the
original stone infill lay up against the bark and no extra infill
was inserted in the relatively short life span of the Pimperne
construct. The essential hypothesis is that had rotting
progressed, over the normal life span of such a house, then there
would have been a growing gap that would be filled with the sort
of objects and artefacts often found during post hole excavation.
The presence of these objects as a post-abandonment feature has
always been difficult to explain and the interpretation offered
by Reynolds, based on these findings, is compelling.

The sort of degradation observed does
not imperil the structure because all loads on the posts are
essentially vertical and, as the hole is infilled, the residual
post above ground level continues to sit on a firm base. This
practice mimics the situation observed with what is seen with
more recent cruck-framed farm buildings, where ultimately the
support pillars end up on top of a raised stone plinth. In fact,
this very process and its success is proof that the building
design, both for the Pimperne construct and for the cruck-frame
barns, results in vertical loading of the support pillars/posts,
for otherwise these would become laterally displaced.

The porch structure is independent of
the main structure and its deterioration pattern is not as
regular. This may be why post holes around supposed porches are
at best distorted and at worst obscure !

"Destroying" the outer wall
proved to be the most arduous of all, requiring the use of sledge
hammers. The wattle work, once the daub had been removed, was
found to be dry and strong and had not become embrittled in the
way that exposed field fences routinely and rapidly deteriorate.
This must contribute to the stability and longevity of such
constructs as this. In a similar manner to the main structural
posts, the vertical stakes supporting the wattle were beginning
to rot back to the surface but less markedly so in the time scale
tested. One suspects the process would end at the ground surface,
out of sight, and that the outer wall would rest happily on the
ground, held in place by the rigid cylindrical shape.

An incidental observation over the life
of the house was that the level of the inner floor varied
according to the wear due to passage of people and to cleaning.
The variety of patterns of the processes involved are detailed in
the Monograph.

Another ancillary record is that after
five years the soil fibre content of the inside floor had fallen
to about 5%, compared with an initial value for the grassland,
prior to construction, of some 24%.

In his final words, Reynolds unwittingly
wrote his own epitaph, judging by statements in his many
obituaries and in the eulogies on the day to celebrate his life's
work :

"That it was an important
construction, which fulfilled all the criteria of the
archaeological evidence, is beyond question."

It is only fitting that this record be
completed with a picture, from the Monograph, of Reynolds
approaching completion of the thatching of the Pimperne House
construct.